This invention relates to a pipe joint and coupling for tubular fluid conduits and to dynamic inter-fitted pipe members and seals in telescoping relationship constructed to provide for axial positional movement relative to a member and remain fluid-pressure-tight, and more particularly to such a joint where the external and outer member is elastically deformed by an external hoop tensile member providing elastic spring biasing to compressively pressure and assure circumferential contact between members and seals for maintaining a leak-proof seal and fitting.
Such expansion joints possessing specific bearing structures such as compressed resilient seals accommodate relative motion between and positional adjustment of one or more pipe members to compensate for alignment and linear thermal expansion or contraction for cryogenic fluid flow in polymer matrix composite (PMC) piping systems for rocket fuel and electronic cooling of lasers or focal plane arrays.
Slip-type expansion joints are used to couple the ends of two pipes or conduits containing high pressure steam or cryogenic fluids in a manner accommodating limited axial movement of the two pipes. In a basic slip-type expansion joint, the annular ring space or cut-out recess between two telescoping pipes is utilized as a stuffing box to receive packing rings and packing material that is installed with compression. The semi-plastic packing material exerts hydraulic-like squeezing force on the sliding surface of the two pipe to maintain a seal and often also to maintain alignment during their relative and limited axial movement. Due to their symmetry, these expansion joints also allow limited rotational relative movement. In general, these basic expansion joints lose their seal due to sealing material creep over time, due to loss of initial packing compression load, and due to vibration, movement, and wear.